The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Accumulators are common components in hydraulic operating and control systems. They are utilized to store a quantity of hydraulic fluid or oil under pressure so that during relatively brief periods of fluid consumption that either exceed the supply capacity of the system pump or during periods that the pump is not operating, there continues to be a sufficient supply of pressurized hydraulic fluid so that operating pressure and flow do not drop below a required minimums.
Such devices may be characterized as passive devices and typically take the form of a cylinder having a combined inlet and outlet port and a piston that is biased toward the inlet/outlet port by a compression spring, a gas on the side of the piston opposite the inlet/outlet port, latching solenoids or other means.
There exist certain problems associated with such devices which are the result of their passive operation. First of all, they generally do not accumulate fluid and thus provide their intended function until the system pump has operated long enough to generate a sufficiently high pressure and provide a quantum of excess fluid which is then directed to and stored in the accumulator. Thus, at system start-up and for a short period thereafter, an accumulator not only typically does not provide the function for which it is intended but will also actually consume pressurized fluid until it is charged thereby effectively lengthening the startup cycle of the system. Moreover, if the charge time of the accumulator is greater than the duration on an operating cycle, little or no operating benefit will be provided by the accumulator. Thus, both during system start-ups and short cycles of operation, a passive accumulator likely will not provide its intended function.
Furthermore, since an accumulator is passive, it cannot create a pressure any higher than that generated by the system pump. If the pump is failing or the system is undergoing a cold start and thus building pressure slowly, not only does the accumulator once again not provide its intended function but it is also unable to achieve any active corrective or compensatory action. The present invention is directed to overcoming these and other shortcomings of conventional, passive fluid accumulators.